GI Pathogens Flashcards by Aimee Supinski

What are the four main pathogenic types of E. coli?

Enterotoxigenic (ETEC), Enteropathogenic (EPEC), Enterohemorrhagic (EHEC), SHIGA TOXIN-producing (STEC)

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What are the three main characteristics of E. coli?

Gram negative, Facultative anaerobe, Has flagella (motile)

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What is the pathogenesis of ETEC (enterotoxigenic E. coli)?

Ingestion of fecal material 2. ETEC colonizes the intestinal mucosa 3. ETEC releases endotoxin (LPS)

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What can occur with a serious rapid case of ETEC (enterotoxigenic E. coli)?

ETEC can progress so rapidly that death occurs due to shock before the development of diarrhea (called enteric colibacillosis)

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How does ETEC cause shock?

It is Gram-negative so it has LPS and it can release a lot of that LPS to cause shock (main virulence factor)

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Which type(s) of E. coli is the most common cause of diarrhea in farm animals (in general)?

Enterotoxigenic (ETEC)

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What is the main virulence factor released by ETEC that causes disease?

The release of endotoxins (LPS)

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What are the two major classes of enterotoxins produced by ETEC?

Heat stable (ST) comprised of STa and STb 2. Heat labile (LT)

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What does heat stable A (STa) toxin do?

It reduces the absorption of electrolytes and water from the intestine at villus tips and elevates secretion of Cl- and H2O by crypt cells.

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What does heat stable B (STb) toxin do?

It stimulates increase in prostaglandin E2 levels, probably inducing the duodenal and jejunal secretion of water and electrolytes

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Which form(s) of E. coli cause neonatal diarrhea in calves?

ETEC (enterotoxigenic)

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Which form(s) of E. coli cause diarrhea and dysentery in 2-8 week old calves?

SHIGA TOXIN-producing (STEC)

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Which form(s) of E. coli cause neonatal diarrhea in pigs?

ETEC (enterotoxigenic)

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Which form(s) of E. coli cause post-weaning diarrhea in pigs?

ETEC (enterotoxigenic) and EPEC (enteropathogenic)

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Which form(s) of E. coli cause edema disease in pigs?

ETEC (enterotoxigenic) and EPEC (enteropathogenic)

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Which form(s) of E. coli cause diarrhea in dogs?

EPEC (enteropathogenic)

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What is the main virulence factor of EPEC that causes disease?

Attaching and Effacing (AE) lesions

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How can you diagnose E. coli?

PCR, Monoclonal antibody-based techniques, Culture E. coli from blood samples (in cases of suspected septicemia)

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Why isn’t the isolation/culture of E. coli from feces useful?

Because it is also commonly present in healthy animals

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E. coli is the most common cause of diarrhea in what general age of calves?

< 10 days old

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ETEC is the most common cause of diarrhea in what age of calves?

< 3 days old

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EPEC and EHEC are the most common causes of diarrhea in what general age of calves?

Slightly older calves (2-30 days but can be up to 4 months)

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What is the biggest risk factor for developing E. coli infection in cattle?

Failure of passive transfer (insufficient volume and quality of colostrum)

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True or False: There is a vaccine for E. coli in cattle

True

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What should vaccines and antibodies for E. coli contain?

K99 antigen

What does E. coli cause in neonatal foals?

Septicemia and diarrhea

True or False: E. coli is the primary cause of diarrhea in neonatal foals

False

What is the most frequently encountered 'fimbrial adhesin' in pigs?

F18

What is the E. coli strain in birds called?

Avian-pathogen E. coli (APEC)

Which three diseases can E. coli cause in pigs?

Enteric colibacillosis, Post-weaning diarrhea, Edema disease

Which disease caused by ETEC is the most common in neonatal piglets?

Enteric colibacillosis

Which disease caused by E. coli is the most common in piglets after 1-2 weeks of weaning?

Post-weaning diarrhea

What else can you see with post-weaning diarrhea in piglets (two)?

Neurological disease, Eyelid and forehead swelling

What disease does Shiga toxin-producing E. coli (STEC) cause in calves?

Diarrhea and dysentery

What disease does Shiga toxin-producing E. coli (STEC) cause in dogs?

Hemolytic uremic syndrome (HUS)

What disease does Shiga toxin-producing E. coli (STEC) cause in pigs?

Edema disease (ED)

What is the pathogenesis of STEC in dogs (four)?

1. Ingestion 2. Attachment and colonization 3. Toxin production 4. Systemic Effects

What is the pathogenesis of STEC in pigs (four)?

1. Ingestion 2. Attachment and colonization 3. Toxin production 4. Systemic Effects

What are the classic two virulence factors produced by STEC?

Shiga toxins, Attaching and Effacing (AE) lesions

True or False: E. coli can also cause non-enteric infections

True

True or False: E. coli affects older animals more harshly

False

What are the three main characteristics of Salmonella?

Gram-negative, Facultative anaerobe, Has flagella (motile)

True or False: All Salmonella serovars (serotypes) are host specific

False

Which serovars of Salmonella are host specific?

Salmonella typhi (humans), Salmonella gallinarum (poultry), Salmonella abortusovis (sheep)

Which serovars of Salmonella are not host specific?

Salmonella typhimurium, Salmonella enteritidis

What is the pathogenesis of Salmonella?

1. Infects small and large intestine enterocytes 2. Salmonella's flagella allow it to move through the mucus layer to reach the surface of the enterocyte 3. Salmonella attaches to enterocyte cell surface via adhesins 4. Type 3 secretory system injects proteins into the enterocyte that cause it to endocytose the Salmonella into a Salmonella containing vacuole.

The lesions and clinical signs of salmonellosis are attributable to which four things?

1. An enterotoxin that disrupts Cl- channels and produces a secretory diarrhea 2. The stimulation of enterocyte death 3. Acute inflammation that can locally cause diarrhea and damages vascular endothelium 4. Endotoxin-induced damage to vascular endothelium

What four clinical signs are typical of Salmonella?

1. Vasculitis 2. Thrombosis 3. Ischemia 4. Infarction

What are the five clinical forms of Salmonella?

1. Peracute septicemia 2. Acute enteritis 3. Chronic enteritis 4. Infarction 5. Abortion

Salmonellosis primarily causes clinical disease in?

Farm animals (can be individual or sporadic outbreak)

What does a fecal culture for Salmonella with heavy growth usually indicate?

Infection

What does a fecal culture for Salmonella with light growth usually indicate?

Carrier status

True or False: Serotype identification can be performed for Salmonella

True

What does the isolation of Salmonella from blood or tissues indicate?

Septicemia

What does rising titers of Salmonella indicate?

An active infection

True or False: Dog and cats rarely get salmonellosis

True

True or False: The isolation of Salmonella from the feces of a dog or cat is insufficient to make a diagnosis of salmonellosis

True

True or False: Cats and dogs can be Salmonella carriers

True

Which three species of Salmonella can infect the oviduct of birds and be transmitted through eggs?

Salmonella pullorum, Salmonella gallinarum, Salmonella enteritidis

What disease does Salmonella pullorum cause specifically in birds?

Pullorum disease or Bacillary white diarrhea

What disease does Salmonella gallinarum cause specifically in birds?

Fowl typhoid

What is paratyphoid?

A non-host adapted Salmonella infection in birds that is usually subclinical

Which two strains of Salmonella cause paratyphoid?

Salmonella enteritidis or Salmonella typhimurium

What is the most common serotype involved in human cases of salmonellosis due to external contamination of eggs?

S. typhimurium

What is the most common serotype involved in human cases of salmonellosis due to internal contamination of eggs?

S. enteritidis

What type of Salmonella do reptiles get?

Salmonella arizonae

True or False: Salmonella infection in turtles, snakes and lizards have been a source of outbreaks of human infection

True

True or False: Reptiles rarely demonstrate any symptoms of Salmonella infection but can become lifelong carriers.

True

True or False: Salmonellosis is zoonotic

True

What is the biggest risk factor for salmonellosis?

Stress

True or False: Carnivores are resistant to Salmonella infections

True

What are the main characteristics of Lawsonia intracellularis?

Gram-negative, Obligate intracellular

What are the four different forms of Lawsonia intracellularis?

1. Porcine intestinal adenomatosis (PIA) 2. Proliferative hemorrhagic enteropathy (PHE) 3. Necrotic enteritis (NE) 4. Regional ileitis (RI)

What is PIA characterized by?

The proliferation of glandular epithelium

What is PHE characterized by?

The proliferation of intestinal epithelium and blood loss in intestinal lumen

What is RI characterized by?

Strong proliferation of the tunica muscularis of the ileum. Also observed in horses, dogs, cats

What is the pathogenesis of Lawsonia intracellularis (three)?

1. After ingestion, L. intracellularis arrives in the ileum and will infect the villous crypt cells 2. The intestinal tissue will thicken by proliferation of stem cells in the crypts 3. Finally, the maximally thickened intestinal wall will have a functional loss of the mucosa

What might you see in the GI tract of pigs with Lawsonia intracellularis infection (three)?

1. Yellow fibrinonecrotic casts can form in the ileum 2. Hemorrhagic form is characterized by the passage of hemorrhagic or black, tarry feces. 3. Characteristically thickened and corrugated ileum

True or False: Lawsonia intracellularis can be diagnosed with a culture

False

How can you treat Lawsonia intracellularis in pigs (two)?

Antibiotics, Vaccine

True or False: Other species can get Lawsonia intracellularis

True

What do you see in horses with infection of Lawsonia intracellularis (four)?

1. Hypoproteinemia 2. Emaciation 3. Thickening of mucosa (jejunum and ileum) 4. Severe hyperplasia of crypt epithelium

What are three characteristics of Clostridia species?

Gram-positive, facultative anaerobe, spore forming

Clostridium perfringens strains are classified into five toxinotypes based on what?

The production of four major toxins (α, β, ε, ι)

What common lesions do you see with Clostridium perfringens?

"Redgut" (the small intestine is reddish-purple and filled with blood)

Clostridium perfringens Type A causes which diseases in each species?

Poultry: Necrotic enteritis, Pigs: Necrotizing enterocolitis, Horses: Hemorrhagic mucosal necrosis, Cattle: Enterotoxemia and sudden death

What clostridial species produces an enterotoxin CPE that causes disease in humans?

Clostridium perfringens Type A

Clostridium perfringens Type D causes which diseases in each species?

Enterotoxemia and pulpy kidney in lambs, calves, goats, horses, and cattle

What toxin does Clostridium perfringens Type D produce?

Epsilon toxin (ε)

What specific clostridial pathogen is responsible for 25% of cases of antibiotic-associated diarrhea?

Clostridium difficile

Which four clinical signs does antibiotic associated diarrhea cause?

Diarrhea, colitis, pseudomembranous colitis, fulminant colitis

What does Clostridium difficile cause in neonatal pigs?

Colitis (specifically edema of the spiral colon)

How can you determine which clostridial species is causing disease?

Use ELISA to test what type of toxins the species is producing

What pathogen causes Tyzzer's disease?

Clostridium piliforme

Which two lesions does Tyzzer's disease cause in cats and dogs?

1. Multifocal periportal hepatic necrosis and icterus 2. Necrotic ileitis or colitis

What is the biggest risk factor for Clostridia infections?

Dysbiosis (disruption of normal gut flora)

How can you diagnose Clostridia infections?

ELISA for toxin detection (gold standard), culture

How can you prevent Clostridia infections?

There is a vaccine that protects against 7 types of Clostridium

Which pathogen causes swine dysentery?

Brachyspira hyodysenteriae

What is a common clinical sign of swine dysentery?

Very mucousy feces

What pathogen causes porcine colonic spirochaetosis (PCS)?

Brachyspira pilosicoli

What are characteristics of Campylobacter species?

Gram-negative, microaerophilic, commensals of intestines and reproductive tract

Can humans get campylobacteriosis?

Yes

What are two characteristics of Yersinia species?

Gram-negative, facultative anaerobes

What type of environment do yersiniosis infections occur in?

Cold, wet weather

What main disease does Helicobacter cause in dogs?

Chronic gastritis (not 100% proven though)